1. Field of the Invention
The present invention relates to a magnetic disk device that incorporates a driving unit for driving a magnetic disk and can be mounted to and removed from the body of an apparatus, and an electronic apparatus including the magnetic disk device and a body for mounting the magnetic disk device thereto.
2. Description of the Related Art
A removable magnetic disk device that can be mounted to and removed from the body of various apparatuses is one type of magnetic disk device usable in, for example, a vehicle-installed electronic apparatus, an information appliance, or a video recorder. This type of magnetic disk device is disclosed in Japanese Unexamined Patent Application Publication No. 6-176555 and PCT Japanese Translation Patent Publication No. 2001-502103.
In this type of magnetic disk device, a hard disk is mounted as a recording medium in a case formed of a hard metal or synthetic resin. In addition, a rotary driver for rotationally driving the hard disk, a magnetic head unit for recording digital signals onto the hard disk and reproducing the digital signals recorded on the hard disk, a control circuit for controlling driving operations of the rotary driver and the magnetic head unit, a digital signal processing circuit, an interface circuit, etc., are mounted in the case.
The case has a predetermined thickness and a rectangular shape. Connector means connected to the various circuits is disposed at the front portion of the case.
A connector for connecting with the connector means is disposed at the body of an apparatus. The various circuits in the case and circuits of the body of the apparatus are connected by mounting the magnetic disk device to the body of the apparatus and fitting the connector means at the case to the body connector.
Unlike a related magnetic disk device that has a hard disk mounted thereto and is fixed in a computer or various information apparatuses, the removable magnetic disk device can be removed from the body of the apparatus. Therefore, the removed magnetic disk device needs to be protected from shock that is produced, for example, when it is dropped.
As disclosed in the aforementioned Japanese Unexamined Patent Application Publication No. 6-176555 and PCT Japanese Translation Patent Publication No. 2001-502103, a dampener is installed in the case of the magnetic disk device in order to protect the rotary driver and the magnetic head unit from shock produced, for example, when the magnetic disk device is dropped.
In the removable magnetic disk device, the use of a soft elastic member having a low elastic modulus is used as the dampener for protecting the rotary driver and the magnetic head unit in the case may increase the error rate of the recording operation and that of the reproducing operation.
In a magnetic disk device used for high recording density, the recording track density of the hard disk is high, the recording/reproduction track width of the magnetic head is small, and the linear recording density along the tracks is high. In this type of magnetic disk device, in order to prevent damage to a recording surface of the hard disk, sliding friction force between a magnet head chip and the recording surface of the hard disk is reduced by forming an air bearing between the magnetic head chip and the recording surface of the hard disk.
In recording information onto and reproducing the information from the hard disk, the magnetic head chip carries out a very precise operation. That is, it searches for a sector in a recording area of the hard disk at a high speed, and instantaneously performs tracking of tracks in the searched sector.
Therefore, when the rotary driver and the magnetic head unit are supported by a soft elastic member in the case, the hard disk and the magnetic head unit tend to move due to vibration generated when the magnetic head unit performs the aforementioned searching operation. When this occurs, the spacing between the magnetic head chip and the surface of the hard disk changes to a value equal to or greater than a standard value, and the tracking operation is affected. As a result, the error rates of data recorded on the hard disk and of data reproduced from the hard disk are increased.
Consequently, it is necessary to use a hard dampener having a high elastic modulus for the dampener disposed in the case of the magnetic disk device. However, such a hard dampener cannot sufficiently protect the components in the case. As a result, a large shock applied to the magnetic disk device when, for example, it is dropped by mistake tends to result in, for example, scratching of a surface of the hard disk or damage to the magnetic head chip.